Breast cancer is the most common type of epithelial cancer among women in the United States. More than 180,000 women are diagnosed with breast cancer each year. About 1 in 8 women in the United States (approximately 12.8 percent) will develop breast cancer during her lifetime. At present there are no curative therapies available for breast cancer that has metastasized from its site of origination. In addition, there is a need for diagnostic markers of use in the detection and staging breast cancers.
DNA microarray profiling of breast tumors has identified distinct subtypes with different clinical outcomes. They include normal breast-like, Her-2 overexpressing, luminal A and B (predominantly ER+), and basal subtypes. Basal-like (referred to as basal) breast cancer (BBC), which includes the A and B subsets, is associated with high grade, poor prognosis, and younger patients. Because of the lack of estrogen, progesterone and epidermal growth factor (Her2) receptor expression, triple negative breast cancer (TNBC), which represents 15-20% of all breast cancer, is not suitable for Her2 targeted and/or anti-estrogen-based therapies. Furthermore, BBC is chemo- and radio-resistant. The resistance and aggressive behavior of this tumor may reflect its enrichment for cancer stem cells (CSC) that have the phenotype of CD44+ and CD24−/lo. CSC are chemo- and radio-resistant and responsible for metastatic spreading and disease recurrence. TNBC cell lines have “stem cell-like” gene expression and are classified as Basal B. A need remains for a method to detect and treat TNBC.